The present invention relates to apparatus for comminuting materials, and particularly to apparatus for guiding waste materials and the like into a shredder and clearing the divided portions of said material from the shredder.
Many devices for comminuting material such as paper waste, plastic waste, rubber tires, and domestic waste include a pair or pairs of generally cylindrical rolls each having axially spaced apart disclike or other rotary cutters which intermesh between spaced apart rotary elements on another one of the rolls. The rotary elements may interact as rotary shears, tearers, or as a hammermill. Depending on its design, such a machine can cut, tear, shred, or pound waste materials and the like into smaller pieces which may then drop or otherpass clear of the intermeshed rolls. A problem often encountered, however, particularly with resilient material such as rubber, is that pieces of the shredded material become caught between the spaced-apart elements of one or both of the rolls, interfering with shredding of additional material.
As has been shown in the past, such materials can be cleared from between the rotary cutting elements and the like of the rolls by stationary sets of elongate members which extend radially inward toward the central axis of the rolls as teeth of a comb to scrape material from between the rotary elements. An example of such a comb-like clearer is shown in Holman U.S. Pat. No. 3,931,935.
Another way to remove the pieces of comminuted material from the shredding apparatus is to use rotating wheels or fingers which pass between the rotary elements of each of the rolls. Such apparatus is shown in Milne U.S. Pat. No. 1,706,935, as well as in Holman.
While such comb-like clearers and rotary clearers are reasonably effective for their purpose, they do have drawbacks. For example, material can quickly accumulate against the faces of the teeth of such comb-like clearers, rubbing against the lateral faces of the discs and thereby increasing the amount of energy needed to rotate the rolls. Pieces of string, yarn, wires, and the like may wrap around the comb teeth and become lodged, causing similar problems. The teeth are also subject to becoming bent.
Rotary clearers may be less likely to become plugged or loaded with shredded material, but energy is required to rotate them, and their complexity adds to the cost of construction and maintenance of a machine including such rotary clearers.
Stationary plates have been provided between the spaced-apart rotary shredding members of paper shredders to clear shredded paper from therebetween, as disclosed in Wagner, U.S. Pat. No. 4,018,392. Such plates, however, have central openings which surround the shafts of the rolls. Pieces of material which may lodge within the central opening in such a plate cannot be easily removed, and contribute to energy waste and wear.
Not only is it necessary to remove cut material from between the spaced-apart discs or other cutters of the rolls of shredding apparatus, but it is also necessary to feed material into the proper location for being shredded by the intermeshed rolls. Although chutes can direct material to generally the proper location, chutes do not guide material the last part of the way into the area where the rolls are actually intermeshed. Large pieces of material and pieces of resilient or slippery material are therefore often likely to bounce about on the infeed side of the intermeshed rolls, rather than being drawn between them.
What is needed, then, is apparatus for use in connection with waste material shredders and the like which have intermeshed rotating rolls, to guide the material to be comminuted into the proper area of the intermeshed rolls, and thereafter to remove the pieces of material from between the spaced-apart rotary cutters or hammers of the rolls to prevent pieces of material from building up and clogging the apparatus. Preferably such apparatus should be sturdy and simple of construction, and should require little or no maintenance.